This invention relates generally to open show cases or display cases of the cold-air-circulation type. More particularly, the invention concerns a method of defrosting show cases of the stated kind and an open show cases adapted to be defrosted by this method.
In an open show case of the above named cold-air-circulation type, in general, frost is deposited on parts such as a cooler and grills at an air ejection nozzle as the show case is operated for cooling, and this deposited frost eventually will give rise to clogging if it is not removed. For this reason, the cooling operation of the cooler is stopped and defrosting operation is carried out after a cooling operation of a certain time.
Heretofore, one known method accomplishing this defrosting operation in a show case of the type referred to above with two or three air flow passages has been to heat the air stream circulating through the cold-air passage containing the cooler and adjacently surrounding the commodity accommodating box by means of an electric heater installed within the cold-air passage on the inlet side of the cooler or by passing hot coolant gas through the cooler while air is caused to flow through all passages in the same state as at the time of normal cooling operation. However, the use of an electric heater increases the electric power consumption, while the use of hot coolant gas requires complicated equipment and is expensive.